[kpatch] [PATCH] livepatch v7: move x86 specific ftrace handler code to arch/x86

[Li Bin <huawei.libin@huawei.com>]

The execution flow redirection related implemention in the livepatch
ftrace handler is depended on the specific architecture. This patch
introduces klp_arch_set_pc(like kgdb_arch_set_pc) interface to change
the pt_regs.

Signed-off-by: Li Bin <huawei.libin@huawei.com>
---
 arch/x86/include/asm/livepatch.h |    5 +++++
 kernel/livepatch/core.c          |    2 +-
 2 files changed, 6 insertions(+), 1 deletions(-)

diff --git a/arch/x86/include/asm/livepatch.h b/arch/x86/include/asm/livepatch.h
index c2ae592..4cdec4e 100644
--- a/arch/x86/include/asm/livepatch.h
+++ b/arch/x86/include/asm/livepatch.h
@@ -21,6 +21,7 @@
 #define _ASM_X86_LIVEPATCH_H

 #include <linux/module.h>
+#include <linux/ftrace.h>

 #ifdef CONFIG_LIVE_PATCHING
 #ifndef CC_USING_FENTRY
@@ -29,6 +30,10 @@
 extern int klp_write_module_reloc(struct module *mod, unsigned long type,
 				  unsigned long loc, unsigned long value);

+static inline void klp_arch_set_pc(struct pt_regs *regs, unsigned long ip)
+{
+	regs->ip = ip;
+}
 #else
 #error Live patching support is disabled; check CONFIG_LIVE_PATCHING
 #endif
diff --git a/kernel/livepatch/core.c b/kernel/livepatch/core.c
index 0004a71..c4c04fd 100644
--- a/kernel/livepatch/core.c
+++ b/kernel/livepatch/core.c
@@ -271,7 +271,7 @@ static void notrace klp_ftrace_handler(unsigned long ip,
 {
 	struct klp_func *func = ops->private;

-	regs->ip = (unsigned long)func->new_func;
+	klp_arch_set_pc(regs, (unsigned long)func->new_func);
 }

 static int klp_disable_func(struct klp_func *func)
-- 
1.7.1